HBASE-25290 Remove table on master related code in balancer implement…

…ation (#3162)

Signed-off-by: Yulin Niu <niuyulin@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/ZNodeClearer.java

@@ -26,13 +26,9 @@
 import java.io.FileWriter;
 import java.io.IOException;
 import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer;
 import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker;
-import org.apache.hadoop.hbase.zookeeper.ZKUtil;
 import org.apache.hadoop.hbase.zookeeper.ZKWatcher;
-import org.apache.hadoop.hbase.zookeeper.ZNodePaths;
 import org.apache.yetus.audience.InterfaceAudience;
-import org.apache.zookeeper.KeeperException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -145,21 +141,6 @@ public static String parseMasterServerName(String rsZnodePath) {
     return masterServerName;
   }
 
-  /**
-   * @return true if cluster is configured with master-rs collocation
-   * @deprecated since 2.4.0, will be removed in 3.0.0.
-   * @see <a href="https://issues.apache.org/jira/browse/HBASE-15549">HBASE-15549</a>
-   */
-  @Deprecated
-  private static boolean tablesOnMaster(Configuration conf) {
-    boolean tablesOnMaster = true;
-    String confValue = conf.get(BaseLoadBalancer.TABLES_ON_MASTER);
-    if (confValue != null && confValue.equalsIgnoreCase("none")) {
-      tablesOnMaster = false;
-    }
-    return tablesOnMaster;
-  }
-
   /**
    * Delete the master znode if its content (ServerName string) is the same
    *  as the one in the znode file. (env: HBASE_ZNODE_FILE). I case of master-rs
@@ -185,25 +166,14 @@ public static boolean clear(Configuration conf) {
     String znodeFileContent;
     try {
       znodeFileContent = ZNodeClearer.readMyEphemeralNodeOnDisk();
-      if (ZNodeClearer.tablesOnMaster(conf)) {
-        // In case of master crash also remove rsZnode since master is also regionserver
-        ZKUtil.deleteNodeFailSilent(zkw,
-          ZNodePaths.joinZNode(zkw.getZNodePaths().rsZNode, znodeFileContent));
-        return MasterAddressTracker.deleteIfEquals(zkw,
-          ZNodeClearer.parseMasterServerName(znodeFileContent));
-      } else {
-        return MasterAddressTracker.deleteIfEquals(zkw, znodeFileContent);
-      }
+      return MasterAddressTracker.deleteIfEquals(zkw, znodeFileContent);
     } catch (FileNotFoundException fnfe) {
       // If no file, just keep going -- return success.
       LOG.warn("Can't find the znode file; presume non-fatal", fnfe);
       return true;
     } catch (IOException e) {
       LOG.warn("Can't read the content of the znode file", e);
       return false;
-    } catch (KeeperException e) {
-      LOG.warn("ZooKeeper exception deleting znode", e);
-      return false;
     } finally {
       zkw.close();
     }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java

@@ -605,17 +605,14 @@ protected void login(UserProvider user, String host) throws IOException {
   }
 
   /**
-   * If configured to put regions on active master,
-   * wait till a backup master becomes active.
-   * Otherwise, loop till the server is stopped or aborted.
+   * Loop till the server is stopped or aborted.
    */
   @Override
-  protected void waitForMasterActive(){
+  protected void waitForMasterActive() {
     if (maintenanceMode) {
       return;
     }
-    boolean tablesOnMaster = LoadBalancer.isTablesOnMaster(conf);
-    while (!(tablesOnMaster && activeMaster) && !isStopped() && !isAborted()) {
+    while (!isStopped() && !isAborted()) {
       sleeper.sleep();
     }
   }
@@ -658,7 +655,7 @@ protected RSRpcServices createRpcServices() throws IOException {
   protected void configureInfoServer() {
     infoServer.addUnprivilegedServlet("master-status", "/master-status", MasterStatusServlet.class);
     infoServer.setAttribute(MASTER, this);
-    if (LoadBalancer.isTablesOnMaster(conf)) {
+    if (maintenanceMode) {
       super.configureInfoServer();
     }
   }
@@ -3703,7 +3700,7 @@ public SyncReplicationReplayWALManager getSyncReplicationReplayWALManager() {
 
   @Override
   public Map<String, ReplicationStatus> getWalGroupsReplicationStatus() {
-    if (!this.isOnline() || !LoadBalancer.isMasterCanHostUserRegions(conf)) {
+    if (!this.isOnline() || !maintenanceMode) {
       return new HashMap<>();
     }
     return super.getWalGroupsReplicationStatus();

hbase-server/src/main/java/org/apache/hadoop/hbase/master/LoadBalancer.java

@@ -48,25 +48,6 @@
  */
 @InterfaceAudience.Private
 public interface LoadBalancer extends Configurable, Stoppable, ConfigurationObserver {
-  /**
-   * Master can carry regions as of hbase-2.0.0.
-   * By default, it carries no tables.
-   * TODO: Add any | system as flags to indicate what it can do.
-   *
-   * @deprecated since 2.4.0, will be removed in 3.0.0.
-   * @see <a href="https://issues.apache.org/jira/browse/HBASE-15549">HBASE-15549</a>
-   */
-  @Deprecated
-  String TABLES_ON_MASTER = "hbase.balancer.tablesOnMaster";
-
-  /**
-   * Master carries system tables.
-   *
-   * @deprecated since 2.4.0, will be removed in 3.0.0.
-   * @see <a href="https://issues.apache.org/jira/browse/HBASE-15549">HBASE-15549</a>
-   */
-  @Deprecated
-  String SYSTEM_TABLES_ON_MASTER = "hbase.balancer.tablesOnMaster.systemTablesOnly";
 
   // Used to signal to the caller that the region(s) cannot be assigned
   // We deliberately use 'localhost' so the operation will fail fast
@@ -164,32 +145,4 @@ Map<ServerName, List<RegionInfo>> retainAssignment(Map<RegionInfo, ServerName> r
 
   /*Updates balancer status tag reported to JMX*/
   void updateBalancerStatus(boolean status);
-
-  /**
-   * @return true if Master carries regions
-   * @deprecated since 2.4.0, will be removed in 3.0.0.
-   * @see <a href="https://issues.apache.org/jira/browse/HBASE-15549">HBASE-15549</a>
-   */
-  @Deprecated
-  static boolean isTablesOnMaster(Configuration conf) {
-    return conf.getBoolean(TABLES_ON_MASTER, false);
-  }
-
-  /**
-   * @deprecated since 2.4.0, will be removed in 3.0.0.
-   * @see <a href="https://issues.apache.org/jira/browse/HBASE-15549">HBASE-15549</a>
-   */
-  @Deprecated
-  static boolean isSystemTablesOnlyOnMaster(Configuration conf) {
-    return conf.getBoolean(SYSTEM_TABLES_ON_MASTER, false);
-  }
-
-  /**
-   * @deprecated since 2.4.0, will be removed in 3.0.0.
-   * @see <a href="https://issues.apache.org/jira/browse/HBASE-15549">HBASE-15549</a>
-   */
-  @Deprecated
-  static boolean isMasterCanHostUserRegions(Configuration conf) {
-    return isTablesOnMaster(conf) && !isSystemTablesOnlyOnMaster(conf);
-  }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterRpcServices.java

@@ -459,8 +459,7 @@ protected RpcServerInterface createRpcServer(final Server server,
       final String name) throws IOException {
     final Configuration conf = regionServer.getConfiguration();
     // RpcServer at HM by default enable ByteBufferPool iff HM having user table region in it
-    boolean reservoirEnabled = conf.getBoolean(ByteBuffAllocator.ALLOCATOR_POOL_ENABLED_KEY,
-      LoadBalancer.isMasterCanHostUserRegions(conf));
+    boolean reservoirEnabled = conf.getBoolean(ByteBuffAllocator.ALLOCATOR_POOL_ENABLED_KEY, false);
     try {
       return RpcServerFactory.createRpcServer(server, name, getServices(),
           bindAddress, // use final bindAddress for this server.

hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java

@@ -45,7 +45,6 @@
 import org.apache.hadoop.hbase.RegionMetrics;
 import org.apache.hadoop.hbase.ScheduledChore;
 import org.apache.hadoop.hbase.ServerMetrics;
-import org.apache.hadoop.hbase.ServerMetricsBuilder;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.YouAreDeadException;
 import org.apache.hadoop.hbase.client.AsyncClusterConnection;
@@ -736,13 +735,6 @@ private int getMinToStart() {
     }
 
     int minimumRequired = 1;
-    if (LoadBalancer.isTablesOnMaster(master.getConfiguration()) &&
-        LoadBalancer.isSystemTablesOnlyOnMaster(master.getConfiguration())) {
-      // If Master is carrying regions it will show up as a 'server', but is not handling user-
-      // space regions, so we need a second server.
-      minimumRequired = 2;
-    }
-
     int minToStart = this.master.getConfiguration().getInt(WAIT_ON_REGIONSERVERS_MINTOSTART, -1);
     // Ensure we are never less than minimumRequired else stuff won't work.
     return Math.max(minToStart, minimumRequired);